Aircraft air pressure measuring instruments are used to measure air pressure pitot tube is commonly used for this purpose. The pitot tube consists of a tube which points directly into the air flow, and which brings the moving air to rest. The resulting pressure within the Pitot tube is called the total pressure (sometimes called stagnation pressure or pitot pressure). Another pressure is the static pressure which exists outside the aircraft's fuselage. The static pressure may be measured with static ports on the aircraft's fuselage, or the pitot tube may itself contain the static ports, wherein it is termed a pitot-static tube. The total pressure and the static pressure are then used to calculate dynamic pressure, which is the pressure caused by the aircraft's motion, and which is proportional to air speed. The equation for determining dynamic pressure (air speed) is:dynamic pressure=total pressure−static pressure
Modern aircraft require measurement of the total air pressure as a critical input into the air data system used to compute many flight-critical parameters such as true airspeed, altitude, temperature, and flight mach number. The total pressure is measured using any number of devices such as a “pitot probe”, “total pressure probe”, or “pitot-static probe”—and for the sake of this disclosure, all such devices are hereafter called “probe”. The front end of the probe that faces into the air flow is called the nose section.
For pressure probes to function correctly on air craft which operate in adverse weather conditions, it is necessary to heat the probe such that no ice can build up in flight to corrupt the measurement. In fact, the FAA has strict oversight as to whether an aircraft is certified for “known icing conditions”—something that can only be achieved using a high-performance heated probe.
Probe designs that exist in the market today all have common design elements as follows:                1) The air passage into the nose section is straight into the body of the probe.        2) In conventional designs heating is applied around the air passage which runs centrally down the probe nose section.        3) Heated probes are large in diameter, not generally less than 0.625 inches at the largest diameter section for pitot-static probes, and not less than 0.50 inches for pitot probes.        4) Conventional heated probes have much higher power consumption, from 150 watts to much higher values        